Capacitor charging solved for time.

In summary, the conversation was about solving the equation V = V0*[1 - e^(-t/RC)] for time, in order to calculate the time at which a charging capacitor reaches a certain voltage. The suggested solution of t = -RC*ln(V/V0) was discussed, but it was pointed out that this may not be accurate due to a step like ln(1+x) = ln(x). It was also mentioned that the lecturer may prefer an intuitive approach rather than solving the equation directly.
  • #1
MidlandSoul
2
0

Homework Statement


Solving the equation: V = V0*[1 - e^(-t/RC)]

Homework Equations


Need to solve this equation for time to calculate the time at which a charging capacitor achieves a certain voltage across it's plates.

The Attempt at a Solution


I solve it as: t = -RC*ln(V/V0) but this doesn't seem to work. Help!
 
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  • #2
it looks like you might have done a step like this: ln(1+x) = ln(x) But this is not true.

Edit: Oh, welcome to physicsforums by the way!
 
  • #3
Show your work step by step & we'll show you where you went wrong.
 
  • #4
BruceW said:
it looks like you might have done a step like this: ln(1+x) = ln(x)
Or rather, ln(1-x) = ln(x)
 
  • #5
Thanks guys. I think our lecturer intends for us to sort of 'have a guess' by inspection and using time constant ratios than actually solve this, so I can leave it for another day, phew!
Thank you for the feedback nonetheless.
 

What is a capacitor?

A capacitor is an electronic component that stores electrical energy in the form of an electric field. It is made up of two conductive plates separated by an insulating material, also known as a dielectric.

How does a capacitor charge?

A capacitor charges when a voltage source, such as a battery, is connected to it. This causes electrons to flow from one plate to the other, creating a potential difference between the plates. As more and more electrons accumulate on one plate, the capacitor becomes fully charged.

What is the equation for calculating the time it takes for a capacitor to charge?

The equation for calculating the time it takes for a capacitor to charge is t = RC, where t is the time in seconds, R is the resistance in ohms, and C is the capacitance in farads.

Can a capacitor be overcharged?

Yes, a capacitor can be overcharged. When a capacitor reaches its maximum capacitance, it cannot store any more charge. If a voltage source continues to supply energy to the capacitor, it can lead to damage or failure of the capacitor.

How can I discharge a capacitor?

A capacitor can be discharged by connecting it to a resistor or a short circuit. This allows the excess charge stored in the capacitor to flow out and return to its equilibrium state.

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